Up through 2040-2060 the gains to the world economy come from some continued growth in the developed countries and China, India, South east asia, and other countries catching up. The per capita assumes that world population grows to about 10 billion and then stays flat.

Assuming energy intensity of 10 megajoules/todays dollar and 10 billion people for a Kardashev level one civilization would mean $5.5 million dollars per person per year. Energy usage would be 55 terajoules per person (15.28 million kwh, 100 GW at 90% capacity factor produces about 800 billion kwh. 1.9 megawatts to generate the 15.28 million kwh)

The highest growth rate path on the table (increasing 3% growth rate every 20 years, 6% for 2010-2030, 9% for 2030-2050, 12% for 2050-2070, 15% for 2070-2090 and 18% for 2090-2100). It would be an economy 12000 times larger than in 2015. Assuming increased energy efficiency relative to GDP generation, I am assuming they will only need about 500 to 1000 times more energy. This would need less than the energy of Kardashev level one. 2* 10 ^16 watts. Kardashev one is about 100 Petawatts (10^17 watts).

William Randolph Hearst was one of the richest men in 1903. He had 28 newspapers read by 20 million people (did not reach that level until 1925). He also had big property. Hearst Castle, but did not own that land until 1919 (construction from 1919-1947).

A more modest modern approximation would still be a multi-millionaire. Someone with a bunch of popular blogs or websites to reach 5 million (lower than the 1920 figure to the 1903 level). Instapundit/Pajamasmedia gets 500,000 page views per day, 12 million per month. Online estimate $10/cpm for about $1.4 million per year in revenue. However, the staff to achieve that went way down. Nice big modern homes (30,000+ sf) are still very expensive, but not Hearst Castle. It would be easier and cheaper (but still expensive) to make a modern approximation of royalty from an earlier period. Certain things become cheaper and easier to make with better technology.